Adhesive composition and process of bonding therewith



iinited States Patent 6 I ADHESIVE COMPOSITIQN AND PROCESS OF BONDINGTI-EREWITH Gunther Nischlt, Leverlrusen-Wiesdorf, and Karl Erwin Miilierand Gtto Bayer, Leverkusen-Bayerwerk, Germany, assignors toFarbenfabriken Bayer Aktlengesellschatt, Leverlrusen, Germany, acorporation of Germany No Drawing. Application February 25, 1953 SerialNo. 338,908

Claims priority, application Germany March 1, 1952 11 Claims. (Cl.154-140) The present invention relates to a new process of bondingmaterials, especially metals.

in copending application Ser. No. 278,508, filed April 25, 1952, We havedescribed unsaturated, carboxyl groups containing polyesters which areobtained by chemical addition of anhydrides of unsaturated carboxylicacids to saturated polyesters having hydroxyl end groups. The said highmolecularweight, unsaturatedpolyesters containing hydroxyl groups can becopolymerized with monomeric vinyl compounds, such as styrene, in thepresence of peroxides and may be used as cast resins.

In accordance with the present invention we have surprisingly found thatmaterials of all kind, especially metals, can successfully be bonded bycausing mixtures of the above described polymerizable compounds of whichone component consists of a carboxyl group containing, unsaturatedcondensation or polymerization product substantially consisting of estergroups and the other component of copolymerizable, unsaturated vinylcompounds, to copolymerize at the connecting seam. The new process isparticularly suitable for bonding metals, cast resins, glass etc.; anextraordinarily good bonding efiect is achieved at temperatures up to100 C. without loosening of the bonded surfaces being possible.

It is, of course, Within the scope of the present invention to uselinear, unsaturated polyesters containing free carboxyl end groups. Suchlinear, unsaturated carboxyl groups containing polyesters can beprepared according to conventional methods by condensation of excessquantities of dicarboxylic acids and maleic acid by thermalesterification.

The addition of unsaturated anhydrides of carboxylic acids is notrestricted to branched polyesters containing hydroxyl groups. As amatter of fact, the said unsaturated anhydrides, can also be added toother high molecular weight compounds containing hydroxyl groups, suchas partly or completely saponified polymers or copolymers of vinylacetate, and may be employed as adhesives after admixing vinylcompounds.

By incoporation of tertiary or secondary amines into the saidunsaturated polyesters containing carboxyl groups (compare copendingapplications Ser. Nos. 313,591, filed October 7, i952, and 320,342,filed November 13, 1952) the bonding process can be carried out alreadyat room temperature or slightly elevated temperatures.

In general, the surfaces are bonded by dissolving peroxides in a mixtureof unsaturated, carboxyl groups containing high molecular weightcondensation or polymerization products and monomeric vinyl compounds,applying this polymerizable mixture in a thin layer, for instance bybrushing, on the roughened surfaces, and hardening with the applicationof slight pressure at temperatures at which decomposition of theperoxides into radicals occurs.

The invention is further illustrated by the following ice exampleswithout being restricted thereto; the parts being by weight.

Example 1 parts of a branched polyester prepared from 2 mols of adipicacid, 0.5 mol of phthalic anhydride and 4 mols of a triol (for instancehexanetriol) by thermal esterification and having the hydroxyl number230 and the acid number 2.1 are heated to 120 C. and 38 parts of maleicanhydride are added thereto. The temperature is kept at 120125 C. for 1hour and, thereafter, 0.1 part of hydroquinone is added. After thetemperature has dropped to 100 C. 59 parts of styrene are run in and thesolution is cooled to room temperature.

1% of benzoyl peroxide is stirred into the copolymerizable solution.This solution may be used to bond metals, plastics etc. at 100 C. byheating the previously slightly roughened surfaces, which have beenprovided with a thin film and immediately superimposed, at

100 C. for 10 minutes.

The copolymerizable solution has an acid number of about -115- TENSILESTRENGTH A'I 20 0.

Aluminum, Overlap- Calculated kgJcm. ping, cm 2 on 1 cru.

AT 100 C.

Example 2 A branched polyester having the acid number 1.8 and thehydroxyl number 230 is prepared by thermal esterification of 365 partsof adipic acid, 74 parts of phthalic anhydride, 480 parts of hexanetrioland 5 parts of p-(N- diphenyl)-diethanolamine. After cooling to C. 100parts of this polyester are reacted with 35 parts of maleic anhydrideand well stirred at 125 C. for 1 hour. After the addition reaction iscomplete 0.1 part of hydroquinone is added, the solution is cooled to100 C. and 59 parts of styrene are introduced.

After addition of 1% of benzoyl peroxide the slightly roughened metalsurfaces, coated with a thin layer, are superposed under pressure andheated to 50 C. for 20 minutes.

The properties as to tear resistance correspond to the samples ofExample 1. The solution of peroxide and Ipolyester is stable at roomtemperature for about 2 ours.

t We-claimL 7 7 V a i 1. A process of bonding materials which comprisesreacting under polymerization conditions a mixture consisting."essentially of (1) a .compoundobtained by reacting anhydrides of alpha,beta ethylenically unsat urated dicarboxylic acids with "polyestersdevoid of aliphatic carbon to carbon unsaturation and having freeliydroxyl groups toproduce polyesterswith end groups" consisting ofhalf-ester groups of alpha, beta ethylenically unsaturated dicarboxylicacids and (2 at least one-monomeric'vinyl'compound at the connectingsurfaces;

A process of bonding materials which comprises re'acting underpolymerization conditions a mixture consisting essentially of 1) a"compound obtained by reacting-anhydrides'of "alpha, be-ta ethylenicallyunsaturated dicarboxylic acids" with; polyesters having free hydroxylgroups an'd containing n'itrogen groups selected from the groupconsisting 'of'secondary and tertiary nitrogen'groups but devoid of:aliphatic carbon to carbon unsaturation to produce polyesters witli'endgroups consisting ofhalfester groups of alpha,-betaethylenically-unsaturateddi- I carboxylic acids and(2)'at,least'onemonomeric vinyl compound 'atithe connecting surfacesr 3.A process of bonding materials as claimed in claim 1 which comprisesicarryiugout the reactionin the presence of peroxides;

a V 4 V a V V of (I) arcompound obtained .by reacting anhydrides ofalpha, beta ethylenically unsaturated dicarboxylic acids with polyestershaving free hydroxyl groups but devoid of aliphatic carbon to carbonunsaturation to produce polyesters with free end groups consisting ofhalf-ester, groups ofmalpha beta ,ethylenically unsaturated dicart iboxylic acidsand (2) at-least one monomeric vinyl com- 1 pound.

9; An adhesivecomposition obtained by reacting underpolymerizationiconditionsa mixture consisting essentially of (1) acompound obtainedzby' reacting anhytdrides of alpha, beta 'ethylenicallyunsaturated dicarboxylic acids with polyesters having free hydroxylgroups and containing nitrogen groups selected from the group consistingof secondary and'tertiary nitrogengroups but devoid of aliphatic carbonto carbonlunsaturation to produce polyesters with free' endgroupsconsistingofhalf-ester groups of alpha,'-betaethylenicallyunsaturated dicar-r ,t boxylic acids and (2) at least one monomericvinyl com- 7 a 7' pound. 1

[OZ An adhesive composition of'claim 8 wherein the;

anhydride used'for producing compo'nenttl) is maleic acid anhydrides t,4. A processofbondingmaterials as claimed in claim a 2; which comprisescarrying, out the reaction in the presence of peroxides:

5. A process of bonding materials"accordingto' the; process of claim 1,wherein theanhydride' usedforipibw ducing component (1).' is maleic acidanhydride.

,6. 'A process of bonding materials according to theproces's"of"claiff1"2; wherein the 'anhydride used 'for producingcomponent (1)" is maleic acid anhydride. 7 t

t 7. A process as claimed in claim 1,'wherein the mate-. 7 rials to beb'ofnded with each other are produced from:

light metals. 1

8. An adhesive composition obtainedby reactingrundert polymerizationconditions .a mixture consisting essentially lllrAnradhesive'icompositionvof claim 9 wherein the anhyidi'ideused"foriproducing component 1) is maleic acid anhydrid'e. V V

References Gitedinthffile of this patent UNT I ED STATES PATENTS 630,022Great Britain Oct; 4, -1949

1. A PROCESS OF BONDING MATERIALS WHICH COMPRISES REACTING UNDERPOLYMERIZATION CONDITIONS A MIXTURE CONSISTING ESSENTIALLY OF (1) ACOMPOUND OBTAINED BY REACTING ANHYDRIDES OF ALPHA, BETA ETHYLENICALLYUNSATURATED DICARBOXYLIC ACIDS WITH POLYESTERS DEVOID OF ALIPHATICCARBON TO CARBON UNSATURATION AND HAVING FREE HYDROXYL GROUPS TO PRODUCEPOLYESTER WITH END GROUPS CONSISTING OF HALF-ESTER GROUPS OF ALPHA, BETAETHYLENICALLY UNSATURATED DICARBOXYLIC ACIDS AND (2) AT LEAST ONEMONOMERIC VINYL COMPOUND, AT THE CONNECTING SURFACES.